<template>
    <div id="slideVerify" class="slide-verify" onselectstart="return false;">
        <canvas ref="canvas" :width="w" :height="h"/>
        <div class="slide-verify-refresh-icon" @click="refresh"/>
        <canvas
            ref="block"
            :width="w"
            :height="h"
            class="slide-verify-block"
        />
        <!-- container -->
        <div
            :class="{
                'container-active': containerActive,
                'container-success': containerSuccess,
                'container-fail': containerFail
            }"
            class="slide-verify-slider"
        >
            <div :style="{ width: sliderMaskWidth }" class="slide-verify-slider-mask">
                <!-- slider -->
                <div
                    :style="{ left: sliderLeft }"
                    class="slide-verify-slider-mask-item"
                    @mousedown="sliderDown"
                    @touchstart="touchStartEvent"
                    @touchmove="touchMoveEvent"
                    @touchend="touchEndEvent"
                >
                    <!-- <div class="slide-verify-slider-mask-item-icon"></div> -->
                    <i class="el-icon-arrow-right"/>
                </div>
            </div>
            <span class="slide-verify-slider-text">{{ sliderText }}</span>
        </div>
    </div>
</template>
<script>
    const PI = Math.PI
    function sum(x, y) {
        return x + y
    }
    function square(x) {
        return x * x
    }
    export default {
        name: 'SlideVerify',
        props: {
            // block length
            l: {
                type: Number,
                default: 42
            },
            // block radius
            r: {
                type: Number,
                default: 10
            },
            // canvas width
            w: {
                type: Number,
                default: 310
            },
            // canvas height
            h: {
                type: Number,
                default: 155
            },
            sliderText: {
                type: String,
                default: 'Slide filled right'
            }
        },
        data() {
            return {
                containerActive: false, // container active class
                containerSuccess: false, // container success class
                containerFail: false, // container fail class
                canvasCtx: null,
                blockCtx: null,
                block: null,
                block_x: undefined, // container random position
                block_y: undefined,
                L: this.l + this.r * 2 + 3, // block real lenght
                img: undefined,
                originX: undefined,
                originY: undefined,
                isMouseDown: false,
                trail: [],
                sliderLeft: 0, // block right offset
                sliderMaskWidth: 0 // mask width
            }
        },
        mounted() {
            this.init()
        },
        methods: {
            init() {
                this.initDom()
                this.initImg()
                this.bindEvents()
            },
            initDom() {
                this.block = this.$refs.block
                this.canvasCtx = this.$refs.canvas.getContext('2d')
                this.blockCtx = this.block.getContext('2d')
            },
            initImg() {
                const img = this.createImg(() => {
                    this.drawBlock()
                    this.canvasCtx.drawImage(img, 0, 0, this.w, this.h)
                    this.blockCtx.drawImage(img, 0, 0, this.w, this.h)
                    const { block_x: x, block_y: y, r, L } = this
                    const _y = y - r * 2 - 1
                    const ImageData = this.blockCtx.getImageData(x, _y, L, L)
                    this.block.width = L
                    this.blockCtx.putImageData(ImageData, 0, _y)
                })
                this.img = img
            },
            drawBlock() {
                this.block_x = this.getRandomNumberByRange(
                    this.L + 10,
                    this.w - (this.L + 10)
                )
                this.block_y = this.getRandomNumberByRange(
                    10 + this.r * 2,
                    this.h - (this.L + 10)
                )
                this.draw(this.canvasCtx, this.block_x, this.block_y, 'fill')
                this.draw(this.blockCtx, this.block_x, this.block_y, 'clip')
            },
            draw(ctx, x, y, operation) {
                const { l, r } = this
                ctx.beginPath()
                ctx.moveTo(x, y)
                ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI)
                ctx.lineTo(x + l, y)
                ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI)
                ctx.lineTo(x + l, y + l)
                ctx.lineTo(x, y + l)
                ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true)
                ctx.lineTo(x, y)
                ctx.lineWidth = 2
                ctx.fillStyle = 'rgba(255, 255, 255, 0.7)'
                ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)'
                ctx.stroke()
                ctx[operation]()
                ctx.globalCompositeOperation = 'overlay'
            },
            createImg(onload) {
                const img = document.createElement('img')
                img.crossOrigin = 'Anonymous'
                img.onload = onload
                img.onerror = () => {
                    img.src = this.getRandomImg()
                }
                img.src = this.getRandomImg()
                return img
            },
            // 随机生成img src
            getRandomImg() {
                // return 'https://picsum.photos/300/150/?image=' + this.getRandomNumberByRange(0, 1084);
                return require(`@/assets/${this.getRandomNumberByRange(
                    0,
                    3
                )}.jpg`)
            },
            getRandomNumberByRange(start, end) {
                return Math.round(Math.random() * (end - start) + start)
            },
            refresh() {
                this.reset()
                this.$emit('refresh')
            },
            sliderDown(event) {
                this.originX = event.clientX
                this.originY = event.clientY
                this.isMouseDown = true
            },
            touchStartEvent(e) {
                this.originX = e.changedTouches[0].pageX
                this.originY = e.changedTouches[0].pageY
                this.isMouseDown = true
            },
            bindEvents() {
                document.addEventListener('mousemove', (e) => {
                    if (!this.isMouseDown) return false
                    const moveX = e.clientX - this.originX
                    const moveY = e.clientY - this.originY
                    if (moveX < 0 || moveX + 38 >= this.w) return false
                    this.sliderLeft = moveX + 'px'
                    const blockLeft = ((this.w - 40 - 20) / (this.w - 40)) * moveX
                    this.block.style.left = blockLeft + 'px'
                    this.containerActive = true // add active
                    this.sliderMaskWidth = moveX + 'px'
                    this.trail.push(moveY)
                })
                document.addEventListener('mouseup', (e) => {
                    if (!this.isMouseDown) return false
                    this.isMouseDown = false
                    if (e.clientX === this.originX) return false
                    this.containerActive = false // remove active
                    const { spliced, TuringTest } = this.verify()
                    if (spliced) {
                        if (TuringTest) {
                            // succ
                            this.containerSuccess = true
                            this.$emit('success')
                        } else {
                            this.containerFail = true
                            this.sliderText = 'try again'
                            this.reset()
                        }
                    } else {
                        this.containerFail = true
                        this.$emit('fail')
                        setTimeout(() => {
                            this.reset()
                        }, 1000)
                    }
                })
            },
            touchMoveEvent(e) {
                if (!this.isMouseDown) return false
                const moveX = e.changedTouches[0].pageX - this.originX
                const moveY = e.changedTouches[0].pageY - this.originY
                if (moveX < 0 || moveX + 38 >= this.w) return false
                this.sliderLeft = moveX + 'px'
                const blockLeft = ((this.w - 40 - 20) / (this.w - 40)) * moveX
                this.block.style.left = blockLeft + 'px'
                this.containerActive = true
                this.sliderMaskWidth = moveX + 'px'
                this.trail.push(moveY)
            },
            touchEndEvent(e) {
                if (!this.isMouseDown) return false
                this.isMouseDown = false
                if (e.changedTouches[0].pageX === this.originX) return false
                this.containerActive = false
                const { spliced, TuringTest } = this.verify()
                if (spliced) {
                    if (TuringTest) {
                        // succ
                        this.containerSuccess = true
                        this.$emit('success')
                    } else {
                        this.containerFail = true
                        this.sliderText = 'try again'
                        this.reset()
                    }
                } else {
                    this.containerFail = true
                    this.$emit('fail')
                    setTimeout(() => {
                        this.reset()
                    }, 1000)
                }
            },
            verify() {
                const arr = this.trail // drag y move distance
                const average = arr.reduce(sum) / arr.length // average
                const deviations = arr.map((x) => x - average) // deviation array
                const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length) // standard deviation
                const left = parseInt(this.block.style.left)
                return {
                    spliced: Math.abs(left - this.block_x) < 10,
                    TuringTest: average !== stddev // equal => not person operate
                }
            },
            reset() {
                this.containerActive = false
                this.containerSuccess = false
                this.containerFail = false
                this.sliderLeft = 0
                this.block.style.left = 0
                this.sliderMaskWidth = 0
                // canvas
                const { w, h } = this
                this.canvasCtx.clearRect(0, 0, w, h)
                this.blockCtx.clearRect(0, 0, w, h)
                this.block.width = w
                // generate img
                this.img.src = this.getRandomImg()
            }
        }
    }
</script>
<style scoped>
  .slide-verify {
    position: relative;
    width: 310px;
  }
  .slide-verify-block {
    position: absolute;
    left: 0;
    top: 0;
  }
  /* .slide-verify-refresh-icon {
    position: absolute;
    right: 0;
    top: 0;
    width: 34px;
    height: 34px;
    cursor: pointer;
    background: url('../assets/icon_light.png') 0 -437px;
    background-size: 34px 471px;
  } */
  .slide-verify-slider {
    position: relative;
    text-align: center;
    width: 310px;
    height: 40px;
    line-height: 40px;
    margin-top: 15px;
    background: #f7f9fa;
    color: #45494c;
    border: 1px solid #e4e7eb;
  }
  .slide-verify-slider-mask {
    position: absolute;
    left: 0;
    top: 0;
    height: 40px;
    border: 0 solid #1991fa;
    background: #d1e9fe;
  }
  .slide-verify-slider-mask-item {
    position: absolute;
    top: 0;
    left: 0;
    width: 40px;
    height: 40px;
    background: #fff;
    box-shadow: 0 0 3px rgba(0, 0, 0, 0.3);
    cursor: pointer;
    transition: background 0.2s linear;
  }
  .slide-verify-slider-mask-item:hover {
    background: #1991fa;
  }
  .slide-verify-slider-mask-item:hover .slide-verify-slider-mask-item-icon {
    background-position: 0 -13px;
  }
  /* .slide-verify-slider-mask-item-icon {
    position: absolute;
    top: 15px;
    left: 13px;
    width: 14px;
    height: 12px;
    background: url('../assets/icon_light.png') 0 -26px;
    background-size: 34px 471px;
  } */
  .container-active .slide-verify-slider-mask-item {
    height: 38px;
    top: -1px;
    border: 1px solid #1991fa;
  }
  .container-active .slide-verify-slider-mask {
    height: 38px;
    border-width: 1px;
  }
  .container-success .slide-verify-slider-mask-item {
    height: 38px;
    top: -1px;
    border: 1px solid #52ccba;
    background-color: #52ccba !important;
  }
  .container-success .slide-verify-slider-mask {
    height: 38px;
    border: 1px solid #52ccba;
    background-color: #d2f4ef;
  }
  .container-success .slide-verify-slider-mask-item-icon {
    background-position: 0 0 !important;
  }
  .container-fail .slide-verify-slider-mask-item {
    height: 38px;
    top: -1px;
    border: 1px solid #f57a7a;
    background-color: #f57a7a !important;
  }
  .container-fail .slide-verify-slider-mask {
    height: 38px;
    border: 1px solid #f57a7a;
    background-color: #fce1e1;
  }
  .container-fail .slide-verify-slider-mask-item-icon {
    top: 14px;
    background-position: 0 -82px !important;
  }
  .container-active .slide-verify-slider-text,
  .container-success .slide-verify-slider-text,
  .container-fail .slide-verify-slider-text {
    display: none;
  }
  .el-icon-arrow-right {
    font-size: 20px;
    margin-top: 12px;
  }
  .slide-verify-slider-mask-item:hover .el-icon-arrow-right {
    color: #fff;
  }
</style>
